Evaluation and Recommendation of a Flow Computer
For Replacing Chart Recorders
ETM 5121 Project Proposal Submitted By
Toby O’Brien
July 20, 2004
1.0 Introduction
This proposal is for the evaluation of electronic flow computers (EFM’s) for use as a
replacement of chart recorders. Enogex, as a natural gas pipeline company uses a
recorder attached to the gas meter (such as an orifice) to convert the physical properties
of the gas pressure and gas temperature to a volumetric flow rate. The chart recorder,
used extensively for many decades, has many opportunities for flow inaccuracy and
requires frequent maintenance checks. The chart recorder uses a bellows to record
pressure, by mechanically moving a pen and marking a circular chart. Additionally the
charts have to be replaced periodically (7, 16, or 31 days) and the charts sent for
integration to determine the gas volume that flowed. Errors in gas flow measurement
using a chart recorder typically range from 5-20% depending on the flowing gas
characteristics.
Flow computers were developed in the late 1980’s and uses electronic
transmitters and a computer to measure gas flow. Approximately 80% of the gas meters
at Enogex are equipped with electronic flow meters rather than the chart recorders. The
remaining chart recorders are due for replacement in 2004-2005.
This proposal first summarizes the opportunity, the objectives of the project, and
the specific deliverables of the project. The alternatives will be described and will
include a summary of the technology, successful use, feasibility, and known
preconceived biases of each alternative. The project approach and evaluation criteria will
be outlined next. Then the project plan will be presented and the use of ETM course
material used in the development of the high level plan will be listed.
2.0 Problem Statement
The gas measurement department has been given verbal approval to replace all the
remaining chart recorders with EFM’s. There are approximately 300 chart recorders
throughout the Enogex pipeline system Formal approval requires an Authorization for
Expenditure (AFE) be submitted containing an economic justification, costs, and project
description. A typical EFM and accessories needed to replace a chart recorder costs
approximately $5,600 each so the value if this project is approximately $1.68 million
dollars. This proposal will address an opportunity to identify possible cost savings by
evaluating EFM model alternatives to determine if the current standard model is the best
choice as replacement of a chart recorder.
3.0 Measures of the Problem
Enogex has standardized on a model of EFM called an Autopilot, made by Thermo
Electron, that meets about 95% of the gas meter installation requirements. This includes
sites with chart recorders, sites with up to three gas meters, sites with valves for control
of pressure or volume done by the EFM, and sites where run-switching of multiple gas
meters is done with an EFM. The Autopilot has many more features than is required at a
typical chart recorder meter. There is an opportunity to save considerable costs by
evaluating the needs of a typical chart recorder site and match those needs to the EFM.
 The EFM currently used as a standard costs approximately $3,200. Based on that
price, the EFM portion of this project will cost $960,000. Other manufacturers of
flow computers have developed EFM’s to target the chart replacement market.
Prices for these models are around $1,900. A potential savings of $390,000 is
possible.
 The current EFM is equipped with more options and features than is typically
need in a chart installation. This proposal will determine the features needed for a
typical chart meter and attempt to match those features to the EFM’s currently on
the market. This project will attempt to qualify the features based on priority, cost
and benefit, needs and wants, and other similar criteria.
 Accessories such as the solar panel size and battery size may be reduced if an
EFM with fewer features is used. The current EFM uses a 20 Watt solar panel
while a unit with fewer features may be able to operate on a 10 Watt solar panel.
The price difference between a 20 Watt solar panel and a 10 watt solar panel is
approximately $80 which could result in a savings of $24,000.
 An EFM is considered a commodity, much like a home PC, so the choice is
between products that perform the same function but are differentiated by their
features. The technical specifications of EFM’s vary widely. The specifications
on such items as transmitter accuracy, calculation compliance to AGA3, data
storage capacity, compatibility options, and software configurability need to be
evaluated and compared to the needs of a chart recorder site. This project will
attempt to compare and measure the difference between the various specifications
among the alternatives.
 The products on the market have various equipment differences such as the
transmitter and electronic components and also have software differences. The
ability of the technician to learn the features may have some influence on the
decision. This project will attempt to measure the friendliness of the hardware for
troubleshooting and software usability.
 The greatest advantage of an EFM over a chart is the accuracy of the flow
measurement. A secondary and long term economic impact of this project is on
the ‘Lost and Unaccounted For’ gas, commonly called L&U. The accuracy of the
flow recorder will have a direct impact on the L&U results of a segment of
pipeline consisting of many input meters and a single output meter. The typical
accuracy of an EFM is 0.5-1.0% while the chart accuracy can range from 5-20%
depending on the flowing gas characteristics. The replacement of chart recorders
will improve L&U because the flow data calculated from electronic signals using
industry standards rather than manual integration of a paper chart. Although the
replacement of chart recorders with an EFM will make a measurable
improvement in L&U, a difference in EFM accuracies can impact L&U as well.
Depending on the evaluation time and management approval time for this project,
a pipeline segment with the most chart replacements will be used to study and
document the impact of chart replacement on L&U as well as the possible impact
of the EFM alternatives on L&U. If the schedule of this project only allows a few
chart replacements then the measurement results of those sites will be included in
the project results.
3.1 Project Objectives
The main objective is to choose the best EFM for the chart recorder replacement project
based on a complete evaluation of the alternatives.
 Determine the specific technical features of a chart replacement EFM. This will
be accomplished by listing the requirements of a chart recorder site and
comparing those requirements to the specifications and field testing results of the
alternatives. Each requirement will be weighted based on criteria such as cost,
importance, benefit, and consequences using the Kepner Tregoe decision making
process. EFM alternatives will also be compared on criteria such as transmitter
accuracy, electronics, and software.
 Identify possible cost savings by better matching the project needs to the EFM
features. The cost of the base EFM, any additional features needed to meet the
chart replacements needs, and the costs of accessories will be compared to the
current standard EFM model and standard accessories. This step may include
working closely with EFM manufacturers to identify opportunities to make
changes to current models that will cut costs while meeting chart replacement
needs.
 Present the results to management as a recommendation. Include the results of
this project in the AFE and submit to management for approval. A formal
presentation might be required to present the findings of this project and answer
questions or clarify the methods used.
 Develop a method of equipment evaluation that can be used on other similar
projects. The methodology used in this project may be used to evaluate other
equipment that may be used in the company. A well documented and easily
followed report will allow review if there are questions about how decisions were
made or what methods were used. As computer technology improves and gets
cheaper it should be expected that EFM’s will continually be evaluated for the
most benefit to the company.
4.0 Specific Deliverables
The specific deliverables as a result of the evaluation of the EFM alternatives are:
 The logical evaluation and decision on the best EFM for chart replacement. A
report of the complete evaluation process will be prepared for upper management
review. The report will include enough information and data so it can be easily
followed and repeated for future evaluations.
 Identification of any cost savings that may be realized as a result of the
alternative choice. The recommended EFM and accessories will be compared on
cost against the current standard EFM. The feature differences, if any, will be
listed along with their corresponding costs.
 Completion and submittal of an Authorization for Expenditure (AFE) for the
replacement of approximately 300 chart recorders with electronic flow computers
(EFM’s). The results of this project will be included in the AFE support

documentation. The AFE submittal process will follow established company
procedures.
A documented standard that can be referenced by others at Enogex that clearly
states the purpose of the project, the methods used in the evaluation, and the
results. The standard may be used as a template for the evaluation of other
standard equipment.
5.0 Alternatives to be Considered
The following alternatives will be evaluated to determine the EFM best suited to replace
chart recorders. These are the alternatives the author is currently aware of but there may
be more added during the project.
5.1 The AutoPilot EFM
Description: One alternative is to continue using the standard EFM which is the
Autopilot model as manufactured by Thermo Electron. This model is in widespread use
throughout the Enogex gas pipeline system. The unit has a multi-variable transmitter for
sensing static and differential pressure. It uses a 3-wire RTD for sensing gas temperature.
The enclosure houses the electronics boards, a sealed lead acid battery, and a microwave
radio. The cost of this EFM, based on past purchases, is $3,200.
Technology: The electronics and computer technology is getting outdated. There are
more features in the AutoPilot than is probably needed at a chart recorder site. The
Autopilot is programmed using an EPROM specifically designed to meet the
specifications of Enogex. Configuration upgrades requires replacing the EPROM chip in
each EFM. The gas flow calculation program meets all American Gas Association
Report Number 3 (AGA3) requirements for gas flow calculations. The software is DOS
based. The Autopilot has 12 analog inputs and 4 discrete inputs or outputs as standard
features.
Feasibility: This choice would not require any study of feasibility because it is currently
the standard for new gas meter installations.
Examples of Successful Use: The Autopilot has been used to replace chart recorders in
the past. It is in wide use throughout the Enogex system and has shown to be reliable.
Enogex has a supply of spare parts and the technicians have become proficient in
troubleshooting the unit. Thermo Electron has conducted many training classes on the
installation, operation, and maintenance of the AutoPilot.
Biases: Enogex technicians probably prefer the AutoPilot because Enogex has installed
approximately 1,000 of them on new gas well meters. The software is DOS based and
somewhat difficult to use in conjunction with Microsoft Windows operating system.
5.2 The Totalflow EFM model Microflo
Description: A company called Totalflow, a division of ABB, Inc, has developed a
model called the Microflo. It targets the chart replacement market. The cost is
approximately $1,900. It has fewer features than the Autopilot. Enogex currently has
other EFM models made by Totalflow that were installed prior to about 1998.
Technology: The latest computer and electronics has been used in this unit. The unit is
programmed using flash memory which can electronically load a new or upgraded
program either locally or remotely. The software is Microsoft Windows based. The
Microflo has no analog inputs and 1 discrete input and 1 discrete output. The Microflo
has been in production about 2 years.
Feasibility: The use of this EFM would require minimal changes in standard
documentation, purchasing practices, spare parts, or training. Since there are other
Totalflow models in the Enogex system there are spare parts and training has been done
as well.
Examples of Successful Use: Totalflow has discontinued manufacturing early model
transmitters and has developed an upgrade system for those transmitters. The upgrade is
based on the Microflo EFM. It includes the Microflo transmitter and electronics that will
fit into an earlier model enclosure. The upgrade been installed by Enogex in
approximately 40 units and has worked well. Technicians have passed on to the author
that other gas companies in the area are using the Microflo.
Biases: The Totalflow software has more configuration options than the AutoPilot.
Technicians generally do not like the Totalflow for this reason. Those technicians who
have learned all the configuration options prefer the Totalflow for this reason. Totalflow
has better local presence and technical support in the area than Thermo Electron.
5.3 The development of a new EFM
Description: Depending on the competition that this project draws between
manufacturers there may be the option for a new model EFM built to Enogex
specifications to fill the need for a chart recorder replacement. A manufacturer can either
build a new unit from scratch or downsize an existing unit to only those features that are
needed.
Technology: The Electronic Flow Computer is basically a computer, programmed to
calculate flow, based on analog or digital inputs of temperature and pressure from an
external device. As electronics and computer technology advance, the speed of the flow
calculation and data storage features improve and become cheaper.
Feasibility: It is not very feasible to develop a new EFM to fit the needs for chart
recorder replacement at Enogex in the next 4-10 months. There are rigorous testing
batteries required to verify the calculations meet AGA3 standards. The testing should be
done by third party labs which may further delay the release. Based on a limited quantity
of 300, it would be difficult to justify the R&D costs. The downsizing of an existing unit
is more feasible but the existing manufacturers’ organizational overhead may prevent
substantial price reductions to the customer and be competitive.
Examples of Successful Use: There are no documented cases of the successful
development of a new EFM to meet the needs of a single customer. The development of
an EFM for an industry-wide need would be more justifiable and probable.
Biases: Thermo Electron, in the development of an EPROM to fit the needs of Enogex,
had many R&D and manufacturing difficulties before they were successful in meeting
our needs. The limited time for this project makes the development of a new EFM
improbable.
5.4 The NuFlo Scanner 1131 model
Description: Another EFM manufacturer is NuFlo. They build the Scanner model 1131
EFM. There is not much known of this model as there are currently not any of these
models in use by Enogex.
Technology: The NuFlo Scanner 1131 is manufactured primarily for international use
and is based on the metric system. There may be difficulties with data formats and
protocols that meet international standards that may be different than US standards.
Feasibility: Enogex currently does not have any experience with NuFlo. A switch to
NuFlo would require training on the hardware and software.
Examples of Successful Use: NuFlo (formerly Barton) is used extensively in other parts
of the world such as South America, India, and Indonesia.
Biases: Since we already have two EFM models in the system, a third model would
probably not be accepted too well. Enogex has legacy systems based on US standards so
a change may lead to upgrades in other areas of the Company. NuFlo’s are not typically
used in the area so not much is known about them.
6.0 Project Approach and Criteria for Evaluating Alternatives
The Manager Gas Measurement and SCADA is the sponsor of this project. The author
will lead the effort of gathering data on the alternatives and evaluating the results. An
informal team may be formed to allow multiple tasks be done in parallel and hopefully
speed up the evaluation process. Assistance from the field technicians may be required
for any field testing of the EFM units. The following is a preliminary list of the specific
tasks to be accomplished and their approximate order:
 Evaluate the typical chart recorder installation to determine the existing
conditions relative to replacement of the chart recorder with an EFM. Define
each area so it can be compared to the features of the EFM.
 Gather the technical data and specifications of each EFM alternative from the
manufacturer. Clarify with the manufacturer any specifications that are not
understood or that varies from industry practice. Include any options, their cost,
and the impact on EFM performance.
 Request a unit from each manufacturer suitable for a field evaluation. The
evaluation will compare the physical unit as well as any software needed to
operate the EFM.
 Evaluate the technical data and specifications. Develop a comparison sheet such
as that used by the Kepner-Tregoe decision making process.
 The performance criteria will include such items as:
1. Physical size, weight, and durability
2. Configurable for non-AGA compliant applications
3. Cost of the base unit and any required features
4. Cost of accessories such as solar panel, battery, manifold, etc.
5. Transmitter accuracy (Static, Differential Pressure, and Temperature)
6. Operating temperature range
7. Software configuration options and user friendliness
8. Upgradeability of the electronics (EPROM vs. flash memory)
9. Upgradeability of the EFM features such as add-on cards
10. Compatibility with the existing microwave radio system
11. Method of communicating data
12. Availability and proximity of technical support
7.0 Project Plan
A rough estimate of the tasks, their duration, and relationships is shown in the Gantt chart below. The capstone project should finish
in early December. The company project may finish later due to internal approval procedures and the existing workload of the
technicians.
8.0 Planned Use of ETM Materials
Based on the plan for evaluation of EFM’s the use of material, concepts, and techniques
learned in the following classes will be used. As the project develops there may be the
opportunity to use other material as well.
 Problem Solving and Decision Making
The Kepner Tregoe method of decision analysis will be used to clarify the purpose of the
decision, evaluate the alternatives available, assess the risks, and make a decision. The
use of decision analysis provides a framework for making logical decisions based on the
evaluation of such things as technical data, musts, wants, benefits, risks, and
consequences.
 Benchmarking
This project may use some concepts learned in benchmarking. If the chart recorder site
criteria are used as the standard then a method of comparing each alternative to this
standard may be helpful in completing the project. The current standard EFM may be
identified as the benchmark also.
 Strategic Project Management
The development and use of a Gantt chart is part of this project. The skills learned in the
project management course will be used to identify the tasks necessary to complete this
project, assign time and relationships to the tasks, create a Gantt chart, and use the chart
as a tool to manage the project. The Gantt chart will be used as a baseline for the
expected task durations and start and ending dates and monitor the progress.
 Engineering Teaming
This project will involve other members of the Measurement department. The creation of
a team consisting of engineers and technicians will provide input and expertise to the
decision making process.